The invention relates to a vehicle lamp provided with a built-in reflector holding a light source in its lamp body and a device for tilting the reflector so as to allow adjustment of the optical axis angle of the lamp.
A known headlamp for a vehicle such as an automobile is provided with a so-called aiming adjusting mechanism in which a reflector installed in the lamp body is tilted in vertical and lateral directions to adjust the optical axis of the reflector. Also, there is a known headlamp provided with an automatic optical axis leveling mechanism that maintains the optical axis of the headlamp at a certain angle in response to the tilting movement of the vehicle body. In either case, the headlamp is required to have a device for tilting the reflector provided overall or inside the lamp so as to adjust the optical axis angle. For this purpose, the latter case, for example, the reflector installed in the lamp body is supported on one or more pivots so as to move tiltably along the direction required to perform optical axis adjustment in vertical and lateral directions relative to the lamp body. An actuator for tilting movement is provided at a position different from the aforementioned pivot so as to move a part of the reflector towards the tiltable direction. As a result, the reflector can be tilted along the required direction to adjust the optical axis angle.
To realize the aforementioned structure in which the part of the reflector is moved by the actuator for tilting movement, the position where the actuator and the reflector are joined is required to combine the linear movement generated by the actuator and the revolution movement about the pivots generated by the reflector. Both movements do not conflict with each other. For this purpose, there has been proposed a joint structure including a ball bearing of groove type (this structure is referred to as a grooved ball bearing hereinafter). FIG. 8 is a schematic view showing the structure of the conventional art. Specifically, the reflector 3 installed in the lamp body 1 is in the tiltable state in the vertical direction at the pivot (not shown). An actuator 31 for tilting movement is fixed to the lamp body 1 at the position opposite to the rear surface of the reflector 3. The actuator 31 for tilting movement has an actuator rod 32 provided with a spherical end 33 having a spherical end portion, which extends toward the optical axis of the lamp. As a result, the actuator rod 32 is structured to perform reciprocating movement along the extending direction upon driving. A stem 3c is integrally formed on the rear surface of the reflector 3 to extend from the position opposite to the actuator rod 32. The grooved ball bearing 21A is fixed to the tip end of the stem 3c using a screw 7.
The grooved ball bearing 21A is formed by resin molding and includes a groove 22 of a semi-tubular shape, a pair of engagement pieces 23 disposed along and at both sides of the groove 22 to protrude therefrom, each end piece 24 of which is bent at an acute angle to face the groove 22, and an anchor part 25 extending outward from the base of the engagement piece 23. The grooved ball bearing is fixed at its anchor part 25 to the stem 3c of the reflector 3 by the screws 7 so that an opening of the groove 22 faces the actuator 31 for tilting movement. The spherical end 33 of the actuator rod 32 is fitted in the gap defined by the groove 22 and the end piece 24 of the pair of engagement pieces 23. The spherical surface of the spherical end 33 abuts against the inner bottom surface of the groove 22 and the pair of end pieces 24. As a result, the spherical end 33 is pivotally supported to allow spherical movement at abutment points. In the above structure, the groove 22 and the engagement piece 23 keep their respective cross sections constant at any point along the axis of the groove, thus allowing a free movement of the spherical end 33 in the direction of the groove axis. When the actuator 31 moves the actuator rod 32 reciprocally in the optical axis direction, the grooved ball bearing 21A secured on the reflector 3 moves as the spherical end 33 moves in the optical axis direction. During this operation, the spherical end 33 is allowed to move along the groove 22 of the ball bearing 21A in its axial direction such that the reflector 3 is allowed to be relatively tilted in a predetermined direction to the actuator rod 32, that is, in the vertical direction in the present case.
The grooved ball bearing 21A is secured at both side anchor parts 25 on the stem 3c of the reflector 3 with screws 7 as described above. Such arrangement, therefore, requires the process of securing two screws 7 to mount the grooved ball bearing 21A onto the reflector, thus increasing man-hours for the assembly process and complicating the assembly work. Furthermore, if the screw 7 is threaded into a hole in an anchor part 25 having a diameter larger than that of the screw with much allowance, the grooved ball bearing 21 is likely to be out of the desired mounting position with respect to the stem 3c. Such dislocation may interfere with alignment between the axis of the actuator rod 32 and the center line of the groove 22 of the ball bearing. This prevents the groove 22 from admitting proper insertion of the spherical end 33 of the actuator rod 32. Even if the insertion is performed, a smooth movement of the actuator rod 32 and the grooved ball bearing 21 may be prevented. In addition, over the extended period of use, the screw 7 may be loosened, which would cause dislocation of the grooved ball bearing 21 relative to the reflector 3. Dislocation of the relative position between the grooved ball bearing 21 and the actuator rod 32 deteriorates the precise tilting of the reflector 3.
An object of the present invention is to provide a vehicle lamp having a device for tilting a reflector, which simplifies the work for assembling the grooved ball bearing and prevents deterioration of tilting movement of the reflector and assures smooth movement by preventing dislocation of the grooved ball bearing.
A vehicle lamp of the present invention is provided with a device for tilting a reflector installed in the lamp body for adjusting the optical axis of the reflector. The device comprises an actuator, for tilting movement disposed on the lamp body, having an actuator rod which is actuated to move linearly along the optical axis of the reflector and a ball bearing secured to the reflector to support pivotally the distal spherical end of the actuator rod so as to convert the linear movement into the tilting movement of the reflector. The ball bearing has first and second anchor parts to be secured to the reflector. The first anchor part is constructed to be secured to the reflector by a fastener means, and the second anchor part is constructed to be fitted with the reflector. The second anchor part has a plurality of fitting walls disposed to define a cross-shaped gap between the fitting walls. The reflector is integrally provided with a cross-shaped boss having a cross-shaped cross section, which can be fitted into the cross-shaped gap. Preferably, the second anchor part has a pin hole at the crossing center of the cross-shaped gap, and the reflector is provided with a pin projecting from the top end of the cross-shaped boss so as to be fitted into the pin hole.
In the present invention, the ball bearing is secured to the reflector by inserting the top end of the cross-shaped boss on the reflector into the cross-shaped gap defined by the walls at the second anchor part, while inserting the pin of the cross-shaped boss into the pin hole in the ball bearing. Then at the first anchor part, the ball bearing is secured to the reflector by the screws. In the process for securing the ball bearing to the reflector, the insertion process is only required at the second anchor part, and fastening the fastening means such as the screw is only required at the first anchor part. This makes it possible to improve assembly workability as a whole. Furthermore the joint system of the cross-shaped gap and boss at the second anchor part prohibits the relative dislocation of the ball bearing with respect to the reflector, thereby ensuring the smooth tilt movement realized by the device for tilting the reflector as well as improving precision in its tilt movement.